Process for manufacture of white clouded glasses, enamels, and glazes



. ytterbium,

UNITED. STATES PATENT OFFICE.

EDUARD nrn'rz, or $50 PAULO, BRAZIL.

PROCESS FOR MANUFACTURE OF WHITE CLOUDED GLASSES, ENAMELS, AND GLAZEB.

No Drawing.

' white clouded fluxes for glass compounds of zircon, tin, titanium, beryllium and similar elements are used, and it has been also proposed already to use at the same time materials containing fluorin as a clouding medium.

Accordingto allprocesses known so far, it was however possible only to obtain pure white opaque glasses, enamels and glazes, if the preparations were artificially cleaned and made completely free from iron. By

means of natural compounds which wereused for the manufacture of the clouding material and even by means of preparations which were only partly freed from iron, only smouched fluxes were obtained, even when discoloring agents were added;

The present invention renders it possible to use natural compounds of zircon, tin, beryllium, titanium, wolfram, tantalum, thorium and the rare earths for pure white clouded glass fluxes. As suitable earths may be mentioned the compounds of cerium, scandium, allium, germanium, yttrium, anthanum. Now the impure natural ores or minerals, or the semimanufactures thereof, which still contain some iron'or other coloring impurities, as well as less thoroughly cleaned semi-manufactures may be used, and a pure white covering enamel or similar glaze be obtained. This surprising Success 1s attained by working the mentioned primary preparations for the clouding substance directly with fluorids into the enamel frit or the glaze-batch.

Care is to be taken to use sufliciently large amounts offfluorids, for instance alkalifluorids, silicofiuords of alkalis, calciumfluorid, natural or artificial cryolite or fluorin compounds. The success of the method is only realized, if there are enough Specification of Letters Patent.

Patented Jan. 18, 1921.

Application filed August 22, 1919. Serial No. 319,191.

fluorids present, which has not been observed hitherto. A corresponding frit of soda, clay, feldspar, quartz, natural zirconia and sllico fluorid of sodium is for instance made 1n the following proportions:

20 parts of quartz,

35 parts of feldspar,

10 parts of soda,

5 parts ofmagnesium carbonate,

. 10 parts of crude zirconia,

20 parts of silico fluorid of sodium.

The cause of the success that a pure white glass 1s obtained, and which has not heretofore been foreseen, mi ht perhaps depend on a volatilization of t e iron through the fluorids. Besides there 'must be sufiicient sllica present.

Owin to the larger quantity of fluorids the finis ed enamel has beside a good covermg power also an easy fusibility, a brighter glaze, and great chemical and thermal re s 1st1ng power. The different batches are not llable to get hair-cracks or craze. Besides the glazes are not poisonous, therefore also suitable for cooking vessels.

Furthermore there is the advantage that the enamels made with zircon or the other mentloned metallic oxids or metallic compounds and fluorids adherelespecially well, so that the are advantageous as a groundenamel. T ey canalso be directly enameled without a ground.

The invention makes it therefore eas to obtain clouded glazes and renders t em cheaper, by making of a white opaque glass directly from the natural impure clouding materials, this white opaque glass moreover being in its whole behavior more favorable. Even if the remain a very long time in the fire, such g azes. remain bright and do not get mat as do some fluor glazes.

Another technical and economical advantage is that borax and borids are not necessary or can be quite replaced without affecting the fluidity and stability of the glazes. With the new process it is possible to get clouded glazes for firing at low temperatures which do not craze and crack' even i if the ceramic bases, that are liable to be the ores of the clouding elements can be directly used and need not be subjected to complicated and expensive chemical purification.

I claim:

1. The manufacture of white clouded glass, enamels and glazes, which comprises embodying unpurified clouding material in the glass, laze or enamel with material containlng su cient fluorin to prevent discolormg.

glass, enamels and glazes, which comprises forming glass, glaze or enamel rich in silica and adding thereto unpurified clouding materials and material containing fluorin sufficient to prevent discoloring. I

3. The method, which comprises embodying in a silicic acid enamel, glaze or glass 2. The manufacture of white, cloudedclouding materials containing iron as an impurity and sufficient material containing fluorin to combine with, the iron present, thereby preventing discoloring due to the presence of iron.

4. The method which comprises embodying in a silicic acid batch of glass, enamel or glaze, unpurified clouding materials and sufficient fiuorid of a metal whose hydroxid is an alkali to prevent discoloring.

In testimony that I claim the foregoing as my invention, I have signed my name in presence of two subscribing witnesses.

EMIL HAGER, EDUARD SIEBRAND. 

